Posted: Fri, Jan 26, 2007, 7:33 AM ET (1233 GMT)
Much of the water and carbon dioxide that Mars had early in its history may still be locked up within the planet, scientists said Thursday. In a paper published in the journal Science, scientists said that the rate of escape of water and carbon dioxide from the Martian atmosphere, as measured by an instrument on ESA's Mars Express spacecraft, is only a small fraction of what was earlier believed. Scientists had previously thought that most of the carbon dioxide and water the planet had early in its history, when the planet was warmed, had been stripped from the atmosphere by solar winds. However, at the current rates of escape, only a small fraction of that original supply would have been lost. Researches argue that either much of the carbon dioxide and water is locked up in hidden subsurface deposits, or that other mechanisms stripped the planet of those volatiles.